As for a semiconductor material that dissolves in a solvent, an organic semiconductor material, for instance, is known. An organic field effect transistor (OFET) is a field effect transistor that includes a thin film (hereinafter referred to as “organic semiconductor film”), which is used as an active layer, formed from an organic semiconductor material. Conventionally, an ink jet method and a spin coating method are generally known as a technology for forming the organic semiconductor film.
However, these methods cannot control the orientation of the molecules in the organic semiconductor film. Accordingly, the formed organic semiconductor film has such a problem that the orientations thereof are not aligned, so that the charge mobility is low. Specifically, the polycrystalline organic semiconductor film has high electric resistance in grain boundaries, and accordingly the charge mobility becomes low.
In response to this problem, a method is disclosed that precipitates crystals from a solution containing an organic semiconductor material, and thereby fabricates an organic semiconductor film having high charge mobility (for instance, Patent Literature 1).